HIV associated neurocognitive disorder (HAND) is a common neurological complication of HIV in the US, and our preliminary data suggest that 31% of HIV+ individuals in Uganda may have HIV dementia, the most severe stage of HAND. HIV- associated psychiatric morbidity is also common. There is also evidence that HIV subtype D is associated with more prevalent neurocognitive morbidity than subtype A in individuals with advanced immunosuppression. However, there are no large population based studies of the neurocognitive or psychiatric status of HIV+ African individuals. The Rakai Health Sciences Program (RHSP), Uganda, offers a unique opportunity to conduct such research. The RHSP can identify HIV+ individuals with moderate (CD4 350-500) and more severe (CD4 ?200) immunosuppression from its population based cohort and HIV clinic services. Rakai District is also one of the few regions where a heterosexual epidemic involves different HIV subtypes (A, D, recombinants), enabling us to compare subtype effects on co-morbidities. Specific aims are: 1. At baseline, to assess whether ART nave HIV+ adults aged ? 20 years with moderate immunosuppression (CD4 350-500), and advanced immunosuppression (CD4 ? 200) experience key neurocognitive/psychiatric co-morbidities, and reduced functional status, compared to age and gender matched HIV- adults in the same Rakai population (the latter will provide normative data as yet unavailable in rural Uganda), 2. To assess the trajectory of these co-morbidities in the HIV+s at two years of follow-up by HIV subtype and level of immunosuppression prior to and after ART initiation, and 3. To define the level of compartmentalized virus in the CSF of individuals with and without dementia stratified by HIV subtype. Hypotheses: 1. ART nave HIV+ individuals with moderate and advanced immunosuppression have higher prevalence and severity of neurocognitive/psychiatric morbidity, and functional disability, compared to HIV- persons in the same communities, 2. ART will reduce the prevalence and severity of co-morbidities, but rates will remain significantly higher than in HIV- persons, 3. Neurological co-morbidities in HIV+ persons, whether or not they are on ART, adversely affect functional status, increasing health and social support needs, 4. HIV subtype D is associated with an accelerated risk of dementia than subtype A among individuals with advanced immunosuppression, 5. Greater viral genetic compartmentalization in the CSF correlates with dementia and is increased with subtype D compared to A. The study will provide epidemiological and clinical data for the development of prevention and support programs related to neurocognitive /psychiatric co-morbidities, and mechanistic data on HIV-related CNS pathology.